Needle free medical connector with expanded valve mechanism and method of fluid flow control

ABSTRACT

A needle free medical connector includes a housing with a first port and a second port. The connector also includes a piston element defining a fluid passageway between the first and second ports. The piston element is movable between flow and non-flow positions. The piston element has a compressible section having a variable inner width that forms a part of the flow path through the connector. As the piston is compressed to the flow position, the compressible section self-expands in width thereby maintaining or increasing the volume of the fluid passageway through the connector. The compressible section has a configuration permitting the continuous flow of fluid through its entirety.

INCORPORATION BY REFERENCE

[0001] We hereby incorporate by reference U.S. Pat. No. 5,676,346 toLeinsing.

BACKGROUND

[0002] The invention relates generally to medical connectors of the typeused in the handling and administration of parenteral fluids, and moreparticularly, to a needle free connector employing a valve mechanismthat compensates for negative fluid displacement, i.e., drawing fluidinto the connector, as the connector returns to its unaccessed statefrom an accessed state.

[0003] Within this specification the terms, “negative-bolus effect,”“positive-bolus effect,” and “no-bolus effect” are used to describe theoperating characteristics of medical connectors as the connector returnsto its unaccessed state from an accessed state. “Negative-bolus” effectdescribes the condition during which fluid is drawn into the connectoras the connector returns to its unaccessed state from an accessed state.“Positive-bolus effect” describes the condition during which fluid isexpelled out of the connector as the connector returns to its unaccessedstate from an accessed state. “No-bolus effect” describes the conditionduring which fluid displacement is neutralized and fluid is neitherdrawn into nor expelled out of the connector as the connector returns toits unaccessed state from an accessed state.

[0004] Needle free medical connectors for injecting fluid into orremoving fluid from an intravenous (“IV”) fluid administration set arewell known and widely used. One conventional type of such a connectorincludes a housing having connection ports at both ends. One connectionport may comprise a female Luer port sized to receive a blunt malecannula, such as a male Luer taper. The other connection port may belocated opposite the first port but in some cases is located at a ninetydegree or other angle to the first port, and comprises a male Luerfitting. In many cases the second port of the connector is permanentlyconnected to IV tubing which in turn is connected to an IV catheter thatcommunicates with a patient's venous system.

[0005] A valve is located within the connector and in most cases usesthe housing of the connector as part of the valve mechanism. When theconnector is accessed, the valve opens an internal fluid passagewaybetween the first and second ports. In some connectors, the internalfluid passageway is defined by the internal boundaries of the connectorhousing; in other connectors it is defined by an internal cannula orhollow spike; and still in others, the internal fluid passageway isdefined by a compressible tubular body that carries the valve mechanism.

[0006] Many needle free medical connectors create fluid displacement asthe connector is accessed and unaccessed. As the connector is accessedby a blunt male Luer cannula tip inserted into the inlet or first portof the connector housing, the valve mechanism is engaged. In someconnectors, the blunt cannula tip penetrates a valve device to establishfluid communication with the internal fluid flow path of the connector.In other connectors, the blunt cannula tip displaces a valve devicewithout penetrating it in order to establish fluid communication withthe fluid flow path. In either case, the volumetric capacity of thefluid flow path is often reduced by the insertion of the blunt cannulawhen accessing the connector. Subsequently, when the blunt cannula isremoved from the connector, the volumetric capacity of the fluid flowpath increases. This increase in the volumetric capacity may create apartial vacuum or pressure reduction in the fluid flow path that maydraw fluid into the connector from the second or downstream end of theconnector. As previously mentioned, the effect of drawing fluid into theconnector in this manner is referred to as a “negative-bolus” effect inthat a quantity, or “bolus,” of fluid is drawn into the partial vacuumor reduced pressure location within the connector.

[0007] A negative-bolus effect as the connector returns to itsunaccessed state is undesirable to some medical care providers andeither a neutral bolus or positive bolus effect is preferred. It istherefore desirable to arrange for a valve mechanism that either doesnot affect the capacity of the internal fluid passageway through theconnector as the connector is returned to its unaccessed state, or thatactually decreases it.

[0008] In one approach, the negative-bolus effect may be reduced oreliminated by clamping the IV tubing between the connector and the IVcatheter prior to removal of the blunt cannula from the connector. Thisprevents the back flow of fluid through the IV catheter and into theconnector. However this is an undesirable approach in that anotherdevice, i.e. a clamp, is necessary and the care provider must rememberto engage the clamp with the tubing. Furthermore, the use of additionaldevices adds expense and causes inconvenience in that they may not beavailable at the time needed. Additional steps are also undesirable inthat most care providers are very busy already and would thereforenaturally prefer to reduce the number of steps in providing effectivecare to patients rather than increase the number.

[0009] In another approach, one that disadvantageously also increasesthe number of steps in the administration of medical fluids, theoperator continually injects fluid into the connector from the maledevice while the male device is being disengaged from the connector. Bycontinuously adding fluid the operator attempts to fill the increasingfluid volume of the fluid flow path through the connector as the maleLuer is being withdrawn, thereby reducing the likelihood of a partialvacuum and thus the likelihood of a negative bolus forming in the fluidflow path. However, this approach is also undesirable in that not onlydoes it add a step but may require some skill in successfully carryingout the procedure.

[0010] The negative-bolus effect may also be reduced by the design ofthe medical connector. As previously mentioned, some medical connectorsinclude an internal cannula or hollow spike housed inside the connectorbody. The internal cannula or spike is positioned to force open a septumupon depression of the septum onto the internal cannula or spike by ablunt cannula. The internal cannula or spike has an orifice at the topand, upon depression of the septum over the internal cannula or spike,the internal cannula or spike is put directly into fluid communicationwith the blunt cannula. The internal cannula or spike provides agenerally fixed-volume fluid-flow path through the connector. Thus, asthe septum returns to its closed position the partial vacuum formedwithin the connector, if any, is not as large as the partial vacuumformed in a connector having a more volumetrically variable internalfluid passageway. A disadvantage of typical connectors having aninternal cannula or spike is a lower fluid-flow rate caused by the smalllumen in the cannula or spike. Additionally, it has been noted that withthe connector design having a fixedly-mounted internal spike and amovable septum that is pierced by that spike to permit fluid flow, suchpierced septum may be damaged with multiple uses and a leaking connectormay result.

[0011] Another connector provides a valve mechanism that includes aflexible body within which is located a relatively rigid leaf spring.The housing of the connector includes an internal cannula and upondepression of the flexible body by the introduction of a blunt cannulathrough a port, the internal cannula forces the leaves of the leafspring apart. The leaves in turn force the top of the flexible bodyapart and open a slit contained therein. The opening of the slitestablishes fluid communication between the accessing blunt cannula andthe lumen of the internal cannula. The expanding leaf spring alsocreates a reservoir-type area between the flexible body and the outerwall of the internal cannula in which fluid is held. As the externalblunt cannula is removed from the connector, the leaf spring andreservoir collapse and fluid is forced out of the reservoir and into theinternal cannula lumen.

[0012] This positive displacement of fluid may result in a positivebolus effect as the valve returns to its unaccessed state. However, thevalve mechanism is relatively complex with a leaf spring beingincorporated into a flexible member which adds some manufacturingconcerns as well as at least one additional part; i.e., the leaf spring.Manufacturing concerns and additional parts can tend to cause expensesto rise, an undesirable effect in the health care industry today wheremanufacturers strive to provide effective products at lower costs.Further, the reservoir-type system does not permit continuous flowthrough the entire expandable flexible body section. Instead, fluidflows into the reservoir and is retained there until the valve isreturned to its unaccessed state.

[0013] Hence, those concerned with the development of medical connectorshave recognized the need for a medical connector having a valvemechanism that avoids the negative-bolus effect by producing either apositive-bolus effect or a no-bolus effect. The need for a medicalconnector that provides these effects without sacrificing fluid-flowrate or structural simplicity has also been recognized. Further needshave also been recognized such as the need for a medical connector thatis less expensive to manufacture, that is efficient in operation, andthat includes fewer parts. The present invention addresses such needsand others.

SUMMARY OF THE INVENTION

[0014] Briefly, and in general terms, the invention is directed to amedical connector having a valve mechanism that provides either apositive-bolus effect or a no-bolus effect, upon deactuation of thevalve mechanism. A connector is provided for controlling the flow offluid, the connector having an internal fluid passageway by which fluidmay flow through the connector, the connector comprises a housing havinga first port and a second port, the first port being adapted to receivea blunt cannula and the second port adapted for fluid communication witha fluid conduit, and a movable element positioned within the housing,the movable element having a first position at which the movable elementblocks fluid flow through the housing and a second position at which themovable element permits fluid flow through the housing, the movableelement comprising a head defining a bore forming a part of the fluidpassageway through the connector, the head being configured such thatwhen the movable element is in the second position, the bore self-opensto permit fluid flow, the head being further configured such that whenthe moveable element is in the first position the bore moves to a closedconfiguration preventing fluid flow, and a compressible section definingan inner conduit forming a part of the fluid passageway through theconnector, the inner conduit having a width moveable between a firstwidth and a second width, the compressible section being configured sothat when the moveable element is in the second position thecompressible section self-expands so that the inner conduit has thesecond width, the inner conduit being further configured so that whenthe moveable element is in the first position the inner conduit moves tothe first width, wherein the first width is smaller than the secondwidth.

[0015] In more detailed aspects, the first and second widths of theinner conduit of the compressible section are selected such that thefluid passageway has a first volume when the movable element is in thefirst position and a second volume when the movable element is in thesecond position, the second volume being larger than the first volume.Further, the first and second widths of the inner conduit of thecompressible section are selected such that the fluid passageway has afirst volume when the movable element is in the first position and asecond volume when the movable element is in the second position, thesecond volume being approximately the same as the first volume. Also,the inner conduit of the compressible section is configured such thatfluid may continuously flow through the entire inner conduit when themovable element is located in the second position.

[0016] In other more detailed aspects, the connector further comprises asupport tube having opposing ends, the support tube defining a lumenextending between the opposing ends, one end being in fluidcommunication with the second port and the lumen forming a part of theinternal fluid passageway through the connector. The support tubecomprises a wall, the wall defining a slot providing a fluid pathbetween the exterior of the tube and the lumen. The support tube isconfigured in relation to the moveable element such that, when themovable element is in the second position, the lumen and slot of thesupport tube are positioned, at least in part, within the inner conduitof the compressible section such that fluid may flow through the innerconduit of the compressible section, through the slot, through the lumenof the support tube, and through the second port of the housing.

[0017] In yet other more detailed aspects, the inner conduit of thecompressible section has opposing first and second ends, the first endbeing adjacent the bore of the head, and the movable element defines anorifice located at the second end of the inner conduit, the orificeforming part of a flow path extending from the bore, through the innerconduit, and out of the inner conduit through the orifice. Further, thelumen and slot of the support tube extend, at least in part, to alocation outside the inner conduit of the compressible section when themovable element is at the second position, and said flow path furtherextends from the orifice, through the slot, and into the lumen at thelocation outside of the inner conduit.

[0018] In further more detailed aspects, the moveable element furthercomprises a spring section connected to the compressible section, andsaid flow path further extends from the orifice, and into the springsection whereby the spring section provides a portion of the internalfluid passageway. The spring section is extended when the moveableelement is in the first position and when extended, the spring sectionhas a first internal volume, and the spring section is compressed whenthe moveable element is in the second position and when compressed, thespring section has a second internal volume, the second internal volumeof the spring section being greater than the first internal volume ofthe spring section whereby the internal volume of the portion of theflow path provided by the spring section is greater when the springsection is compressed.

[0019] In other features, the housing includes a narrowed regionadjacent the first port, the head of the movable element being locatedin the narrowed region when the movable element is in the firstposition, the narrowed region being dimensioned so as to cause the boreof the head to close. Additionally, the housing includes a constrictedregion, the compressible section being located in the constricted regionwhen the movable element is in the first position, the constrictedregion being dimensioned so as to cause the width of inner conduit ofthe compressible section to move to the first width.

[0020] Yet further, the compressible section is connected to the head,and the moveable element further comprises a spring section connected tothe compressible section, the spring section being adapted to urge themovable element to the first position at which the compressible sectionis placed within the constricted region. In a more detailed aspect, thehead, and the compressible section, and the spring section are molded asan integral moveable element.

[0021] In additional features, the compressible section comprises aplurality of relatively flexible membrane elements and a plurality ofrelatively stiff wall elements, the membrane elements connectingtogether adjacent edges of the wall elements. Further, the membraneelements are adapted to fold radially inwardly when the inner conduithas the first width.

[0022] These and other aspects and advantages of the invention willbecome apparent from the following detailed description and theaccompanying drawings, which illustrate by way of example the featuresof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a side view of an assembled medical connector thatincorporates aspects of the present invention, showing a first portsurrounded by thread elements for receiving a blunt connector and athreaded cuff, and a second port comprising a blunt male connector;

[0024]FIG. 2 is an exploded perspective view of the medical connector ofFIG. 1 showing the three components of the medical connector of thisembodiment, including an upper housing portion, a piston element, and alower housing portion;

[0025]FIGS. 3 and 4 are elevational views, at right angles to eachother, of the piston element shown in FIG. 2;

[0026]FIG. 5 is an end view of the self-opening head of the pistonelement of FIG. 3 showing its normally-open marquise-shaped bore andhaving the same orientation as the piston element of FIG. 3;

[0027]FIG. 6 is a perspective view in partial cross section of thepiston element of FIG. 2 with the section taken across the line marked6-6, showing the self-expanding inner conduit in its normally expandedcondition;

[0028]FIG. 7 is a sectional elevation of the medical connector of FIG.1, showing the connector in a non-accessed state with the piston elementin its first position in which the self-opening bore of the piston headis closed to fluid flow by the narrowed first port of the housing andthe compressible section has been compressed to its first width by anarrowed region of the housing;

[0029]FIG. 8 is an enlarged perspective view of the first port of theconnector of FIG. 1 showing the self-opening head of the piston elementin the first position with the marquise shaped bore closed to fluidflow;

[0030]FIG. 9 is a sectional view of the medical connector of FIG. 7,taken across the line marked 9-9 showing the compressible section in itscompressed configuration;

[0031]FIG. 10 is a sectional elevation of the medical connector of FIG.1, showing the connector in an accessed state with the piston elementhaving been moved to its second position in which the self-opening boreof the piston head has opened to fluid flow and the self-expandingconduit of the compressible section has expanded to its normal“as-molded” state, or second width, for increased internal volume;

[0032]FIG. 11 is a sectional view of the medical connector of FIG. 7taken across line 11-11 showing the self-expanding conduit of thecompressible section at its normal “as-molded” state, or second widthfor increased internal volume;

[0033]FIG. 12 is a detail view of the portion of FIG. 10 showing inenlarged detail the interaction of the slot and lumen in the supporttube with the self-expanded inner conduit of the compressible section,and the action of the spring section on the compressible section;

[0034]FIG. 13 is a cross-sectional view of the enlarged details of FIG.12 showing the self-expanding inner conduit at its second width, thesupport tube, the slot in the support tube, and showing in particularorifices existing at the base of the inner conduit that permit fluidflow from all parts of the conduit into the slot of the support tube sothat there is continuous fluid flow through the entire inner conduit;

[0035]FIGS. 14 and 15 are schematic depictions of an operationalprinciple utilized by a medical connector that incorporates aspects ofthe present invention; and

[0036]FIGS. 16 through 18 are perspective views of the piston elementshowing alternative configurations of the spring section.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0037] Referring now in detail to the drawings in which like numeralsrefer to like or corresponding elements among the several figures, thereis illustrated in FIG. 1 a side external view of a medical connectorthat includes various aspects of the present invention. The particularconnector configuration exemplified in the figures is for illustrationpurposes only. The connector may be embodied in different configurationsincluding, but not limited to, Y-connectors, J-loops, T-connectors,tri-connectors, PRN adapters, slip Luers, tubing engagement devices,access pins, vial adapters, blood tube adapters, bag access pins, ventedadapters, and others. The drawings are for illustration purposes only.

[0038]FIG. 1 presents an embodiment of a medical connector 20 having ahousing 22 that is formed of an upper housing portion 24 and a lowerhousing portion 26. The upper housing portion 24 has a first port 28,that in this case is a female Luer connector port with thread elements30 located about the exterior. The lower housing portion 26 terminatesin a second port 32 that, in this case, comprises a male Luer connector34 defining a lumen 35 (lumen not visible in FIG. 1) and with a threadedlocking collar 36 (threads not visible in FIG. 1). Together, the upperhousing 24 and the lower housing 26 form the connector housing 22. Thehousing 22 may be molded of a material containing a phosphorescentcolorant to render the connector 20 visible in a darkened room or may beformed of a transparent and/or opaque material.

[0039] Turning now to FIG. 2, an exploded, somewhat perspective view ofthe connector 20 of FIG. 1 is shown. The connector 20 comprises threeparts in this embodiment: the housing 22 (see FIG. 1 for numeral 22)that comprises the upper housing portion 24 and the lower housingportion 26. The connector 20 also includes a movable element or pistonelement 38. As will be described in more detail below, the pistonelement 38 is mounted over a support tube 40 that is formed as part ofthe lower housing portion 26. In one embodiment, the support tube 40extends proximally from the center of the lower housing portion 26 andhas an inner lumen 42 extending the length of the tube, and in the wall44 of the tube, a longitudinal slot 46 is formed that may extend thelength of the tube. In the embodiment shown, the lower housing portion26 also includes a vent 53 used for the escape or intake of air from orto the housing during movement of the piston element 38. In anotherembodiment, there may not be a vent.

[0040] The housing of the embodiment shown in FIGS. 1 and 2 includesdetails that aid in manufacturing and that lower the costs ofmanufacture. As an example, the exterior surface of the upper portion 48of the lower housing portion 26 is molded to include a crown shapedouter shell that has several crown points 50. Although not shown in FIG.2, the interior of the lower portion 52 of the upper housing portion 24is molded to include a complementary shaped pattern to the crown-shapedlower housing portion. The crown shapes 50 of the lower housing portion26 mate closely with the complementary crown shapes (not shown) of theupper housing portion 24 thereby facilitating a snap-fit assembly of themedical connector housing. A snap ring 51 is also included in the lowerhousing portion 26 and holds the upper housing portion 24 in place onthe lower housing portion 26 once the upper housing portion has beenforced over the snap ring 51. The geometry of the crown shapes alsoprevents rotation of the upper housing portion 24 with the lower housingportion 26 when they are snapped together. Permanent assembly of theupper housing portion with the lower housing portion may also beachieved by means such as ultrasonic weld geometry, a spin weld,bonding, or by other means in other embodiments. This design has beenfound to result in an efficiently manufactured housing assembly that isaccurately assembled, that is quickly and efficiently snapped into asecure assembly.

[0041] Referring now to FIGS. 3 and 4 enlarged views of a resilientlydeformable piston element 38 are presented. The same piston element 38is shown in both views, each rotated at right angles to each other. Thepiston element includes three main sections; a piston head 54, acompressible section 56, and a compressible section or spring section58. The compressible section is located between the head and the spring.The piston element may suitably be molded as one piece from a resilientmaterial such as silicone or rubber.

[0042] The piston head 54 includes a top portion 60 that is ellipticalin outer shape, and a bottom, tapered shoulder section 62 that iscircular in plan cross-section. Referring now also to FIG. 5, amarquise-shaped bore 64 is formed in the elliptically-shaped top section60. Located between the head 54 and the shoulder section 62 is anelliptical-conical section 61 that assists in causing themarquise-shaped bore to tend to remain open. For further details on theoperation of the piston head, see U.S. Pat. No. 5,676,346 to Leinsing,which is incorporated herein by reference. Although not shown in FIGS.3, 4, or 5, the compressible section 56 includes a self-expanding innerconduit that forms one of the aspects of the invention.

[0043] Referring now to FIG. 6, a perspective cross-sectional view ofthe compressible section 56 is shown. As can be clearly seen, thecompressible section includes an inner conduit 66 formed by two opposingrelatively stiff wall elements 68 that are connected together by twoopposing relatively flexible membrane elements 70. The interconnectionof the wall elements 68 results in the inner conduit 66 with a width 72.It should be noted that the term “width” is not used herein in arestrictive sense; that is, it is not used to indicate the dimension inany particular direction within the inner conduit. It is used instead ina general sense to indicate the interior cross-sectional opening size ofthe inner conduit measured at right angles to the longitudinal axis ofthe moveable element.

[0044] The membrane elements 70 are adapted to fold inwardly when aradially compressive force is applied to the compressible section 56.Due to the relative stiffness of the wall elements 68, the length of theinner conduit 66 remains substantially constant under such radiallycompressive force. When the radially compressive force is removed orreduced, the inner conduit 66 is self-expanding and tends to expanduntil it is open, as shown in FIG. 6, under the force provided by theresilient material of the compressible section 56.

[0045] It can be noted that the inner conduit shown in FIG. 6 has anunusual opening shape. However, the advantageous nature of this openingshape will be apparent when later figures are discussed below.

[0046] Referring now to FIG. 7, the connector 20 of FIG. 1 is shown invertical cross-sectional format. It should be noted that the connectordepicted in FIG. 7 is in an unaccessed state. That is, no blunt cannulahas been inserted into its first port 28 for fluid communication throughthe connector.

[0047] The upper housing portion 24 has sections of varying internaldiameter. The internal section directly adjacent the first port 28includes a standard ANSI Luer taper portion 100 that incorporates a veryslight inward taper. The center portion 102 has a larger internaldiameter than the Luer taper portion 100 and is separated from the Luertaper portion 100 by a tapered lock portion 104. The bottom portion 106of the upper housing portion 24 has a larger internal diameter than thecenter portion 102 and is separated from the center portion by a taperedramp portion 108. Thus, in relation to the bottom portion 106, thecenter portion 102 represents a constricted region, and, in relation tothe center portion 102, the Luer taper portion 100 represents a narrowedregion. The bottom portion 106 has an inner diameter large enough topermit the inner conduit 66 to self-expand.

[0048] Referring now to both FIGS. 7 and 3, the spring section 58 isshown and will be discussed in more detail. In the embodiment shown, thespring section 58 is configured to include a plurality of relativelystiff annular wall portions 110 (only two of which are indicated by thenumeral 110 to preserve clarity in the drawings), connected to eachother by relatively flexible annular hinges 112, together forming thespring section. The annular wall portions 110 disposed at the center ofthe spring section have an hourglass shape 113 (see FIG. 3) that permitstheir bending at the center point. The hourglass shape and the hingesresult in compression of the spring 58 in a controlled elastic fashionto assume a bellows-like shape in response to an axially compressiveforce, as will be described in relation to FIG. 10 below.

[0049] The inner diameter of the spring section 58 is selected to allowpositioning of the spring over the support tube 42 and the outerdiameter of the spring is selected to allow positioning of the springwithin the housing 22. The spring is easily slidable over the supporttube 42 in the embodiment shown but when a compressive force is appliedto the spring, the support tube prevents the spring from buckling andassists the spring in a controlled change to a bellows-type shape.

[0050] In the unaccessed state of the connector 20 as shown in FIG. 7,the spring section 58 of the piston element 38 urges the compressiblesection 56 through the ramp portion 108 of the upper housing portion 24into the relatively constricted center portion 102. The location of thecompressible section 56 in this constricted location causes compressionof the compressible section and the inner conduit, as shown in FIG. 9. Aradially compressive force is applied to the compressible section thatcauses the membrane elements 70 to fold inwardly and the stiff wallelements 68 to move toward each other as shown in FIG. 9, therebysubstantially reducing the width 72 of the inner conduit 66 to a firstcompressed width, that is much less than the second expanded width ofthe inner conduit 66 shown in FIG. 6. Had there been any fluid in theinner conduit 66 when it had its second width, as shown in FIG. 6, most,if not all, of that fluid would be expelled as the inner conduit assumedthe first width shown in FIG. 9.

[0051] The cross-sectional view of FIG. 7 shows the interaction of thethree parts of the connector of the embodiment discussed. The upperhousing portion 24 includes the first port 28 that comprises a femaleLuer connector port with thread elements 30 located about the exterior,and is securely connected to the lower housing portion 26. The lowerhousing portion 26 includes the second port 32 that comprises the maleLuer connector 34 with a threaded locking collar 36. The internalthreads are visible in FIG. 7. The lower housing portion 26 alsoincludes the support tube 40 integrally formed with the lower housingportion. In this embodiment, the support tube has a length that resultsin its location somewhat within the first housing portion 24 when thecomplete housing has been assembled. This feature is also apparent fromFIG. 2.

[0052] Further, the movable element or piston 38 is shown mounted overthe support tube and extending to the first port 28 of the upper housingportion 24. The piston head 54 is within the narrowed Luer taper region100 of the first housing portion and this narrowing has caused acompressive force to be exerted against the elliptical portion 60 of thepiston head 54, thereby causing the marquise-shaped bore 64 to beclosed. This closed configuration is more clearly shown in FIG. 8 wherethe top of the piston head can be seen and the closed bore 64 is clearlyseen. It should also be noted that this configuration permits easywiping of the piston head before use. This closed bore 64 blocks thefluid flow through the valve in this unaccessed state.

[0053] It should be noted that the fluid volume within the connector 20in this unaccessed state is defined by the open portion in the pistonhead under the closed bore 64, the inner conduit 66 through thecompressible section, the lumen 42 of the support tube and the secondport 32. It is also informative to note that the support tube and secondport are rigid structures and their internal volumes do not change withthe connector being accessed, as will be discussed below. While the bore64 of the piston head may appear to be open in FIG. 7, it is closed. Theparticular orientation of the cross section in FIG. 7 results in themarquise-shaped bore being shown along its length, and thus has theappearance of being open. However, a perspective view of the top of thepiston head, such as that shown in FIG. 8, demonstrates that the bore isclosed.

[0054] In further reference to FIG. 7, the spring includes a base 114that is mounted at the base 116 of the support tube 40. The spring maybe held in place at the base of the support tube by friction, adhesive,or other means. For example, in the present embodiment, the movableelement 38 is placed in the lower housing portion 26 with the springsection 58 over the support tube 40 and the base 114 positioned asshown, and the upper housing portion 24 is placed over the movableelement 38 and secured to the lower housing portion as described above.Because the dimensions of the upper housing portion and the lowerhousing portion are such that there is constant, although limited, axialcompressive pressure placed on the movable element 38, the springsection 58 tends to stay in position as shown. This may be referred toas a pre-load force. Incorporated U.S. Pat. No. 5,676,346 to Leinsingmay be referred to for further details. Extending proximally from thecenter of the base 116 is the support tube 40. Extending distally fromthe base is the male-Luer taper connector 34 having a lumen 35 that iscoaxial with the lumen 42 of the support tube 40.

[0055] Turning now to FIG. 10, the connector 20 in an accessed state isshown. A blunt cannula 130, which is a male Luer connector in this case,has been inserted into the first port 28 into contact with the topsection 60 of the piston element head and has moved the piston elementso that the compressible section 56 is now partially over the supporttube 40. The spring 58 is now compressed.

[0056] As is described in U.S. Pat. No. 5,676,346 to Leinsing, theconfiguration of the piston head results in the bore 64 of the pistonhead being self-opening. That is, the bore 64 is normally open andradial compressive forces must be applied to the piston head to closethe bore. The elliptical-conical portion 61 (see FIGS. 3 and 4) of thepiston element head 54 also uses the axial force from insertion of themale Luer 130 to facilitate the opening of the bore 64. Thus, when themale cannula 130 presses the piston head into the larger interior of thehousing 22 and radial compressive forces are removed from the pistonhead, the bore 64 self-opens to now permit fluid flow through theconnector 20.

[0057] Similarly, the compressible section 56 is configured so that theinner conduit 66 is self-expanding. That is, the inner conduit 66 isnormally at its second width and radial compressive forces must beapplied to the compressible section to close the inner conduit, or toforce it to have its smaller first width. Thus, when the male cannula130 presses the piston head into the larger interior of the housing 22,and radial compressive forces are removed from the compressible section,the inner conduit 66 self-expands to its larger second width that willnow permit a larger fluid volume within the fluid passageway of theconnector 20. This larger width either exactly compensates for thedecrease in length of the fluid passageway through the connector or addsadditional volume to the fluid passageway. As can be seen by referenceto FIG. 10, pressing the male cannula 130 into the connector 20 shortensthe length of the fluid passageway through the connector from the lengthin FIG. 7 and would otherwise thereby reduce the volume of the fluidflow path also. However, the increased width of the inner conduitvolumetrically counteracts this decrease in length. This is discussed inmore detail below in regard to FIGS. 14 and 15.

[0058] In FIG. 10, it is shown that the compressible section 56 and theinner conduit 66 are now located partially over the support tube 40.This arrangement can be seen in greater detail in the enlarged diagramof FIG. 12. The support tube however includes a lumen 42 through whichfluid may flow and a longitudinal slot 46 in the wall 44 of the tubethrough which fluid may continuously flow into and out of the supporttube lumen and into and out of the inner conduit as shown in FIG. 10.Fluid that may reach the spring section will also flow into or out ofthe slot of the support tube so that continuous flow occurs throughoutthe connector when in the accessed state. No reservoirs or dead space ofany nature exist so that each part of the fluid passageway is adaptedfor continuous flow through it.

[0059] Turning now also to FIG. 11 in conjunction with FIG. 10, theinteraction of the support tube 40, its lumen 42, and its slot 46 withthe inner conduit 66 may be seen from another angle. FIG. 11 is a crosssectional view of FIG. 10, which is a connector in the accessed state.In FIG. 11, a possible orientation of the slot of the support tube withthe inner conduit wall is shown. In this configuration, the slot 46 ofthe support tube resides against one of the stiff walls 68 of the innerconduit. This particular positioning does not prevent fluid flow throughthe inner conduit because orifices 132 are provided at the bottom of theinner conduit to provide for fluid flow between the inner conduit andthe proximal portion of the spring section. The enlarged diagram in FIG.13 shows the orifices 132 more clearly. In the accessed state, the pointof connection between the spring section 58 and the compressible section56 may be configured to define the orifices 132 through which thesupport tube 40 protrudes. Thus, at the distal end of the inner conduit66, a plurality of gaps or orifices 132 may be defined between thepiston element 38 and the support tube 40 which collectively provide afluid flow path between all portions of the inner conduit 66 and theproximal section 133 (see FIG. 12) of the spring section 58, from whencefluid may flow into the lumen 42 of the support tube via the slot 46.

[0060] Thus, the compressible section 56 is configured so that when theconnector 20 is accessed by a blunt cannula 130, fluid may flowcontinuously through the entire inner conduit 66 without a reservoirbeing developed at any point in which fluid may be trapped, held, orretained. The piston element 38 is configured to provide a larger fluidpassageway width at the location of the compressible section 56 when theconnector is in the accessed state, as shown in FIG. 10, thus increasingthe volume of the fluid passageway or keeping it the same as the volumeof the fluid passageway in the unaccessed state, as shown in FIG. 7.

[0061] It will be appreciated that, when the slot 46 of the support tubeis oriented so that it is facing one of the membrane elements 70 in FIG.11, fluid may flow directly between the lumen 42 of the tube and theinner conduit 66 via the slot 46 or in parallel with fluid flow throughthe orifices 132.

[0062] To briefly reiterate, in the accessed state as shown in FIG. 10,the internal fluid passageway through the connector 20 is through thebore of the piston element, through the head of the piston element,through the entire inner conduit 66, through the lumen 42 of the supporttube, and through the second port 32. It will be appreciated that flowmay be reversed when fluid is withdrawn through the connector. It shouldbe noted that in comparison to FIG. 7, the internal fluid passageway ofFIG. 10 has been shortened by the amount that the blunt cannula 130 hasentered the first port 28, or, put another way, the amount by which theinner conduit 66 now covers the support tube 40. However, theself-expansion of the inner conduit to a greater width hasvolumetrically compensated for the decrease in length of the internalfluid passageway. Conversely, as the blunt male connector 130 iswithdrawn from the first port 28, the internal fluid passageway throughthe connector will lengthen, but at the same time the width of the innerconduit will decrease. If the decrease in width decreases the volume offluid in the internal fluid passageway of the connector by an amountgreater than the increase in length causes an increase in volume, abolus of fluid may be expelled by the connector 20 through the secondport.

[0063] In further detail, the inner conduit will be discussed. Referringto FIGS. 9 and 11, the membrane elements 70 may be adapted to foldinwardly when a radially compressive force is applied to thecompressible section. Due to the relative stiffness of the wall elements68, the length 134 of the inner conduit 66 remains substantiallyconstant under such radially compressive force. Where the radiallycompressive force is removed or reduced, the inner conduit 66 isself-expanding and tends to expand under the force provided by theresilient material of the compressible section 56.

[0064] In regard to the spring section 58, the piston element 38resiliently deforms so as to permit the annular portions 110 toalternatingly deform inwardly and outwardly, while allowing rotation tooccur mainly at the hinges 112, as exemplified in FIG. 10. A comparisonof the two spring section 58 configurations shown in FIGS. 7 and 10 willreveal that when in the configuration of FIG. 10, the spring section 58also contributes to the increased internal fluid passageway through theconnector resulting from insertion of the male Luer into the connector.Because the longitudinal slot 46 extends substantially along the entirespring section length in the configuration of FIG. 10, fluid maycontinuously flow within the spaces 59 formed between the spring sectionand the support tube 40 resulting from the action of the hinges 112during compression of the spring section.

[0065] Referring to FIG. 7, the spring section 58 is in an extendedconfiguration when the moveable element 38 is in the first position;i.e., the connector 20 has not been accessed by a male Luer. As can beseen, the spring section is located quite close to the support tube 40along its entire length. At this location, the spring section has afirst internal volume. When the connector 20 has been accessed and themoveable element 38 has been located at its second position as shown inFIG. 10, the spring section 58 has been compressed. In compression,parts of the spring section remain close to the support tube 40 whileother parts move outwards forming the spaces 59 indicated in FIG. 10.Taking the internal volume of the spring section, which includes theparts near and the parts farther away from the support tube 40, thespring section has a second internal volume, and that second internalvolume is greater than the first internal volume (extended, oruncompressed, spring section). Because of this configuration and thefact that the slot in the support tube extends into the spring section,the spring section forms a part of the internal fluid passageway throughthe connector. In the embodiment shown, the spring section contributesto a net volume increase of that internal fluid passageway when theconnector is accessed. Conversely, when the connector is unaccessed;i.e., when the male Luer 130 is being withdrawn, the spring section willcollapse to the configuration shown in FIG. 7 thereby contributing to adecrease in the net volume of the internal fluid passageway through theconnector.

[0066] It will be appreciated that modifications in the shapes of thespring section are possible. Changes may be made to affect flow rate,restoring force, spring section return rate, volume, differential volumebetween compression and extension configurations, sealing, pistonretention, and acceptance of blunt cannulas. Modifications includechanging the number of annular sections, wall thickness and height, ormay include different configurations of the spring section entirely, asexemplified in FIGS. 16-18.

[0067] The use of the support tube 40 also has another advantage.Because it takes up volume in the internal fluid passageway by virtue ofits size, there is less volume for fluid in that passageway when theconnector is not accessed (shown in FIG. 7). This results in a smallerfluid passageway in the unaccessed state than might otherwise exist ifno support tube were present. Because it is rigid, it has a fixed volumethat will not change.

[0068]FIGS. 14 and 15 are schematic drawings that present the concept ofthe adjustment of the volume of the internal fluid passageway through aconnector based on expansion and contraction of a part of thatpassageway. In FIG. 14, a schematic connector 136 is shown that includesan internal fluid passageway 138 having a length 140 linking a firstport 142 with a second port 144. In FIG. 14, the single dashed lineadjacent the first sport 142 is used to indicate the closed bore of thepiston head. Forming part of the fluid passageway 138 is an innerconduit 146 having a first width 148. In FIG. 15, a blunt cannula 150has been inserted into the first port 142 of the connector 136 and hasshortened the internal fluid passageway 138 which now has a length shownby numeral 154. The difference between the length 140 of the internalfluid passageway in FIG. 14 and the length 154 of the internal fluidpassageway in FIG. 15 is shown by numeral 156. If nothing else were tochange, the volume of the internal fluid passageway 138 of FIG. 15 wouldnow be less than that of FIG. 14, and a negative bolus effect could beexpected upon removal of the male cannula 150. However, the width 160 ofthe inner conduit 146 in FIG. 15 has been expanded to be greater thanthe width 148 of the inner conduit of FIG. 14. It will be appreciatedthat, by appropriate selection of the expanded and compressed widths ofthe inner conduit, the volume of the fluid path 138 can be made toincrease, stay the same, or decrease when a blunt cannula is made toaccess the connector 136. Where the volume increases, a positivebolus-effect is created when the cannula is removed from the connector.Where the volume remains the same, a neutral-bolus effect is created,and, where the volume decreases, a negative-bolus effect is created.

[0069] Turning now to the operation of the medical connector 20, theconnector is initially in its unaccessed state or closed position asshown in FIG. 7. The resiliency of the spring section 58 of the pistonelement 38 causes the piston head 54 to be biased into the narrowed ANSILuer taper portion 100. The shoulder 62 of the piston head 54 contactsthe tapered lock portion 104 of the upper housing portion 24 andcontrols the position of the top of the piston head 54 in relation tothe edge of the first port 28 thus forming a swabable surface therewith.The sharp pointed ends of the marquise-shaped bore 64 facilitate a tightseal upon compression of the bore along its minor axis and bycompression of the top section 60 of the piston head 54 along its majoraxis.

[0070] Just prior to accessing the connector with a male Luer connectorat the first port 28, the top surface of the piston head 54 and the edgeof the first port may be cleaned by, for example, passing a sterilizingswab over the smooth surface of the piston head lying flush, slightlybelow, or slightly above the upper surface of the first port. Theconnector is then ready to be accessed by a standard male Luer connectorwith or without a threaded locking collar.

[0071] The tip of a male Luer connector is brought into contact with theproximal surface of the top section 60 of the piston head 54. Theapplication of sufficient pressure causes the spring section 58 of thepiston element 38 to axially contract and to compress in a bellows-likeconfiguration so that orifices 132 are defined between the springsection 58 and the support tube 40. As the spring section 58 axiallycontracts, the piston head 54 moves out of the narrowed ANSI Luer taperportion 100 of the upper housing portion 24 and into the center portion102. As the piston head 54 clears the tapered lock portion 104 and ismoved into the center portion 102, the larger internal diameter of thecenter portion allows the top section 60 of the piston head toself-expand and to tend to assume its normal elliptical shape and thesame action allows the bore 64 to tend to self-open to assume itsnormally open marquise-shape bore configuration thereby opening a fluidpassageway through the connector and the piston head 54.

[0072] Further, as the spring section 58 contracts under axial pressureof the male Luer tip 130, the compressible section 56 moves in thedistal direction from the constricted center portion 102 of the upperhousing 24 into the larger diameter bottom portion 106 of the upperhousing, allowing the compressible section to self-expand and to assumean expanded configuration. As the compressible section 56 moves in thedistal direction, the support tube 40 will extend into the inner conduit66.

[0073] As the blunt cannula 130 becomes fully inserted in the connector20, the compressible section fully self-expands, thereby expanding thewidth of the inner conduit. Flow may now occur through the connector.The internal fluid passageway through the connector has expanded inwidth to volumetrically compensate for the decrease in length, and fluidflows continuously through every part of the internal fluid passagewayof the connector. Additionally, fluid flows through the entirecompressible section 56 due to the slot 46 in the wall 44 of the supporttube 40 and the orifices 132 that permit fluid flow through the distalend of the inner conduit 66 into the proximal section 133 of the springsection and into the slot 46.

[0074] When the blunt cannula 130 is withdrawn from the connector 20 toallow the connector to return to the non-accessed state, the restoringforce generated by the spring section 58 of the piston element 38 causesthe compressible section 56 to be urged proximally past the ramp section108 into the constricted confines of the center section 102 of the upperhousing portion 24 and thus into the compressed condition where theinner width 72 of the inner conduit decreases to its first width, asshown in FIG. 7. Thus, the volume of the fluid passageway through theconduit may decrease, depending on the selected dimensions of thecompressible section 56 and its inner conduit 66. If so, a bolus offluid that was within the inner conduit will be expelled through thesecond port 32. Simultaneously, the elliptical top portion 60 of thepiston head 54 is guided by the tapered lock section 104 into the ANSILuer taper section 100 where it is once again urged into a narrowedcircular shape to close off the orifice 64 and reestablish a positiveseal against fluid flow through the connector 20.

[0075] Thus there has been shown and described a new and useful valvefor use in medical connectors that provides a controllable bolus effect.Depending on the expanded and compressed widths selected for the innerconduit 66 of the compressible section in relation to the configurationof the balance of the piston element 38, a positive-bolus,neutral-bolus, or negative-bolus effect can be achieved as the connectoris placed in an unaccessed state from an accessed state.

[0076] It will be apparent from the foregoing that while particularembodiments of the invention have been illustrated and described,various modifications can be made without departing from the spirit andscope of the invention. Accordingly, it is not intended that theinvention be limited, except as by the appended claims.

What is claimed is:
 1. A connector for controlling the flow of fluid,the connector having an internal fluid passageway by which fluid mayflow through the connector, the connector comprising: a housing having afirst port and a second port, the first port being adapted to receive ablunt cannula and the second port adapted for fluid communication with afluid conduit; and a movable element positioned within the housing, themovable element having a first position at which the movable elementblocks fluid flow through the housing and a second position at which themovable element permits fluid flow through the housing, the movableelement comprising: a head defining a bore forming a part of the fluidpassageway through the connector, the head being configured such thatwhen the movable element is in the second position, the bore self-opensto permit fluid flow, the head being further configured such that whenthe moveable element is in the first position the bore moves to a closedconfiguration preventing fluid flow; a compressible section defining aninner conduit forming a part of the fluid passageway through theconnector, the inner conduit having a width moveable between a firstwidth and a second width, the compressible section being configured sothat when the moveable element is in the second position thecompressible section self-expands so that the inner conduit has thesecond width, the inner conduit being further configured so that whenthe moveable element is in the first position the inner conduit moves tothe first width, wherein the first width is smaller than the secondwidth.
 2. The connector of claim 1 wherein the first and second widthsof the inner conduit of the compressible section are selected such thatthe fluid passageway has a first volume when the movable element is inthe first position and a second volume when the movable element is inthe second position, the second volume being larger than the firstvolume.
 3. The connector of claim 1 wherein the first and second widthsof the inner conduit of the compressible section are selected such thatthe fluid passageway has a first volume when the movable element is inthe first position and a second volume when the movable element is inthe second position, the second volume being approximately the same asthe first volume.
 4. The connector of claim 1 wherein the inner conduitof the compressible section is configured such that fluid maycontinuously flow through the entire inner conduit when the movableelement is located in the second position.
 5. The connector of claim 1further comprising a support tube having opposing ends, the support tubedefining a lumen extending between the opposing ends, one end being influid communication with the second port and the lumen forming a part ofthe internal fluid passageway through the connector.
 6. The connector ofclaim 5 wherein the support tube comprises a wall, the wall defining aslot providing a fluid path between the exterior of the tube and thelumen.
 7. The connector of claim 6, wherein the support tube isconfigured in relation to the moveable element such that, when themovable element is in the second position, the lumen and slot of thesupport tube are positioned, at least in part, within the inner conduitof the compressible section such that fluid may flow through the innerconduit of the compressible section, through the slot, through the lumenof the support tube, and through the second port of the housing.
 8. Theconnector of claim 7 wherein: the inner conduit of the compressiblesection has opposing first and second ends, the first end being adjacentthe bore of the head; and the movable element defines an orifice locatedat the second end of the inner conduit, the orifice forming part of aflow path extending from the bore, through the inner conduit, and out ofthe inner conduit through the orifice.
 9. The connector of claim 8wherein: the lumen and slot of the support tube extend, at least inpart, to a location outside the inner conduit of the compressiblesection when the movable element is at the second position; and saidflow path further extends from the orifice, through the slot, and intothe lumen at the location outside of the inner conduit.
 10. Theconnector of claim 8 wherein: the moveable element further comprises aspring section connected to the compressible section; and said flow pathfurther extends from the orifice, and into the spring section wherebythe spring section provides a portion of the internal fluid passageway.11. The connector of claim 10 wherein: the spring section is extendedwhen the moveable element is in the first position and when extended,the spring section has a first internal volume; and the spring sectionis compressed when the moveable element is in the second position andwhen compressed, the spring section has a second internal volume, thesecond internal volume of the spring section being greater than thefirst internal volume of the spring section; whereby the internal volumeof the portion of the flow path provided by the spring section isgreater when the spring section is compressed.
 12. The connector ofclaim 1 wherein the housing includes a narrowed region adjacent thefirst port, the head of the movable element being located in thenarrowed region when the movable element is in the first position, thenarrowed region being dimensioned so as to cause the bore of the head toclose.
 13. The connector of claim 1 wherein the housing includes aconstricted region, the compressible section being located in theconstricted region when the movable element is in the first position,the constricted region being dimensioned so as to cause the width ofinner conduit of the compressible section to move to the first width.14. The connector of claim 13 wherein: the compressible section isconnected to the head; and the moveable element further comprises aspring section connected to the compressible section, the spring sectionbeing adapted to urge the movable element to the first position at whichthe compressible section is placed within the constricted region. 15.The connector of claim 14 wherein the head, and the compressiblesection, and the spring section are molded as an integral moveableelement.
 16. The connector of claim 1 wherein the compressible sectioncomprises a plurality of relatively flexible membrane elements and aplurality of relatively stiff wall elements, the membrane elementsconnecting together adjacent edges of the wall elements.
 17. Theconnector of claim 16 wherein the membrane elements are adapted to foldradially inwardly when the inner conduit has the first width.
 18. Aconnector for controlling the flow of fluid, the connector having aninternal fluid passageway by which fluid may flow through the connector,the connector comprising: a housing having a first port and a secondport, the first port being adapted to receive a blunt cannula and thesecond port adapted for fluid communication with a fluid conduit; and amovable element positioned within the housing, the movable elementhaving a first position at which the movable element blocks fluid flowthrough the housing and a second position at which the movable elementpermits fluid flow through the housing, the movable element comprising:a head defining a bore forming a part of the fluid passageway throughthe connector, the head being configured such that when the movableelement is in the second position, the bore self-opens to permit fluidflow, the head being further configured such that when the moveableelement is in the first position the bore moves to a closedconfiguration preventing fluid flow; a compressible section defining aninner conduit forming a part of the fluid passageway through theconnector, the inner conduit having a width moveable between a firstwidth and a second width, the compressible section being configured sothat when the moveable element is in the second position thecompressible section self-expands so that the inner conduit has thesecond width, the inner conduit being further configured so that whenthe moveable element is in the first position the inner conduit moves tothe first width, wherein the first width is smaller than the secondwidth; and wherein the inner conduit is configured such that fluid maycontinuously flow through the entire inner conduit when the movableelement is in the second position.
 19. The connector of claim 18 whereinthe first and second widths of the inner conduit of the compressiblesection are selected such that the fluid passageway has a first volumewhen the movable element is in the first position and a second volumewhen the movable element is in the second position, the second volumebeing larger than the first volume.
 20. The connector of claim 18wherein the first and second widths of the inner conduit of thecompressible section are selected such that the fluid passageway has afirst volume when the movable element is in the first position and asecond volume when the movable element is in the second position, thesecond volume being approximately the same as the first volume.
 21. Theconnector of claim 18 further comprising a support tube having opposingends, the support tube defining a lumen extending between the opposingends, one end being in fluid communication with the second port and thelumen forming a part of the internal fluid passageway through theconnector.
 22. The connector of claim 21 wherein the support tubecomprises a wall, the wall defining a slot providing a fluid pathbetween the exterior of the tube and the lumen.
 23. The connector ofclaim 22 wherein the support tube is configured in relation to themoveable element such that, when the movable element is in the secondposition, the lumen and slot of the support tube are positioned, atleast in part, within the inner conduit of the compressible section suchthat fluid may flow through the inner conduit of the compressiblesection, through the slot, through the lumen of the support tube, andthrough the second port of the housing.
 24. The connector of claim 23wherein: the inner conduit of the compressible section has opposingfirst and second ends, the first end being adjacent the bore of thehead; and the movable element defines an orifice located at the secondend of the inner conduit, the orifice forming part of a flow pathextending from the bore, through the inner conduit, and out of the innerconduit through the orifice.
 25. The connector of claim 24 wherein: thelumen and slot of the support tube extend, at least in part, to alocation outside the inner conduit of the compressible section when themovable element is at the second position; and said flow path furtherextends from the orifice, through the slot, and into the lumen at thelocation outside of the inner conduit.
 26. The connector of claim 25wherein: the moveable element further comprises a spring sectionconnected to the compressible section; and said flow path furtherextends from the orifice, and into the spring section whereby the springsection provides a portion of the internal fluid passageway.
 27. Theconnector of claim 26 wherein: the spring section is extended when themoveable element is in the first position and when extended, the springsection has a first internal volume; and the spring section iscompressed when the moveable element is in the second position and whencompressed, the spring section has a second internal volume, the secondinternal volume of the spring section being greater than the firstinternal volume of the spring section; whereby the internal volume ofthe portion of the flow path provided by the spring section is greaterwhen the spring section is compressed.
 28. The connector of claim 18wherein the housing includes a narrowed region adjacent the first port,the head of the movable element being located in the narrowed regionwhen the movable element is in the first position, the narrowed regionbeing dimensioned so as to cause the bore of the head to close.
 29. Theconnector of claim 18 wherein the housing includes a constricted region,the compressible section being located in the constricted region whenthe movable element is in the first position, the constricted regionbeing dimensioned so as to cause the width of inner conduit of thecompressible section to move to the first width.
 30. The connector ofclaim 29 wherein: the compressible section is connected to the head; andthe moveable element further comprises a spring section connected to thecompressible section, the spring section being adapted to urge themovable element to the first position at which the compressible sectionis placed within the constricted region.
 31. The connector of claim 30wherein the head, and the compressible section, and the spring sectionare molded as an integral moveable element.
 32. The connector of claim18 wherein the compressible section comprises a plurality of flexiblemembrane elements and a plurality of relatively inflexible wallelements, the membrane elements connecting together adjacent edges ofthe wall elements.
 33. The connector of claim 32 wherein the membraneelements are adapted to fold radially inwardly when the inner conduithas the first width.
 34. A connector for controlling the flow of fluid,the connector having an internal fluid passageway by which fluid mayflow through the connector, the connector comprising: a housing having afirst port and a second port, the first port being adapted to receive ablunt cannula and the second port adapted for fluid communication with afluid conduit; a movable element positioned within the housing, themovable element having a first position at which the movable elementblocks fluid flow through the housing and a second position at which themovable element permits fluid flow through the housing, the movableelement comprising: a head defining a bore forming a part of the fluidpassageway through the connector, the head being configured such thatwhen the movable element is in the second position, the bore self-opensto permit fluid flow, the head being further configured such that whenthe moveable element is in the first position the bore moves to a closedconfiguration preventing fluid flow; a compressible section defining aninner conduit forming a part of the fluid passageway through theconnector, the inner conduit having a width moveable between a firstwidth and a second width, the compressible section being configured sothat when the moveable element is in the second position thecompressible section self-expands so that the inner conduit has thesecond width, the inner conduit being further configured so that whenthe moveable element is in the first position the inner conduit moves tothe first width, wherein the first width is smaller than the secondwidth, the inner conduit being configured such that fluid maycontinuously flow through the entire inner conduit when the movableelement is located in the second position; and a support tube having afirst end and a second end with the second end being in fluidcommunication with the second port, the support tube having a lumenforming a part of the internal fluid passageway through the connector,the support tube having a wall that defines the lumen and a longitudinalslot formed through the wall and into communication with the lumenwhereby fluid may flow into and out of the lumen through thelongitudinal slot; wherein the lumen and slot of the support tube arelocated within the inner conduit of the compressible section when themovable element is in the second position whereby fluid may flow throughthe inner conduit of the compressible section, through the slot, throughthe lumen of the support tube, and through the second port of thehousing.
 35. The connector of claim 34 wherein: the inner conduit of thecompressible section has a first end and a second end; and the movableelement also comprises an orifice located at the second end of the innerconduit that provides a flow path between the inner conduit and alocation of the fluid passageway that is outside of the inner conduit.36. The connector of claim 35 wherein: the lumen and slot of the supporttube extend to a location outside the inner conduit of the compressiblesection when the movable element is at the second position; and theorifice provides a flow path between the inner conduit and the slot andthe lumen of the support tube at the location outside of the innerconduit.
 37. The connector of claim 36 wherein: the moveable elementfurther comprises a spring section connected to the compressiblesection, the spring section located over the lumen and slot of thesupport tube that extend to the location outside the inner conduit; andthe orifice provides the flow path through the spring section.
 38. Theconnector of claim 37 wherein: the spring section is extended when themoveable element is in the first position and when extended, the springsection has a first internal volume; and the spring section iscompressed when the moveable element is in the second position and whencompressed, the spring section has a second internal volume, the secondinternal volume of the spring section being greater than the firstinternal volume of the spring section; whereby the internal volume ofthe portion of the flow path provided by the spring section is greaterwhen the spring section is compressed.
 39. The connector of claim 34further comprising a narrowed region adjacent the first port of thehousing at which the head of the movable element is located when themovable element is in the first position, the size of the narrowedregion selected so as to cause the bore of the head to close to preventfluid flow through the fluid passageway of the connector.
 40. Theconnector of claim 34 further comprising a narrowed region adjacent thefirst port of the housing at which the compressible section is locatedwhen the movable element is in the first position, the size of thenarrowed region selected so as to cause the inner conduit of thecompressible section to move to its second width.
 41. The connector ofclaim 40 wherein: the compressible section is connected to the head; andthe moveable element further comprises a spring section connected to thecompressible section, the spring section being adapted to urge themovable element to the first position at which the compressible sectionis placed within the narrowed region.
 42. The connector of claim 41wherein the head, and the compressible section, and the spring sectionare molded as an integral element from a resilient material.
 43. Theconnector of claim 34 wherein the compressible section comprises aplurality of substantially inflexible wall elements and a plurality ofsubstantially flexible membrane elements, the membrane elementsconnecting together adjacent edges of the wall elements.
 44. Theconnector of claim 43 wherein the membrane elements are adapted to foldradially inwardly when the inner conduit has the second width.
 45. Amethod for controlling the flow of fluid, the method comprising:inserting a blunt cannula in a first port of a housing to establishfluid communication with the housing; moving a movable element that ispositioned within the housing from a first position to a secondposition, the movable element comprising a head with a bore that isclosed to prevent fluid flow through the housing when the movableelement is in the first position and is self-opening when the movableelement is in the second position to permit fluid flow, a compressiblesection with an inner conduit, the inner conduit having a first widthwhen the movable element is in the first position and self-expanding toa second width that is larger than the first width when the movableelement is at the second position; causing fluid to flow continuouslythrough the entire inner conduit when the movable element is located atthe second position; retracting the blunt cannula from the first port ofthe housing; moving the movable element from the second position to thefirst position during the step of retracting the blunt cannula; andmoving the inner conduit from the second width to the first width duringthe step of retracting.
 46. The method of claim 45 wherein the step ofmoving the movable element comprises expanding the inner conduit to thesecond width at which the volume for fluid flow through the connector islarger than when the inner conduit is at its first width.
 47. The methodof claim 45 wherein the step of moving the movable element comprisesexpanding the inner conduit to the second width at which the volume forfluid flow through the connector is approximately the same as when theinner conduit is at its first width.
 48. The method of claim 45 wherein:the step of moving the movable element further comprises moving theinner conduit over a support tube having a lumen forming a part of theinternal fluid passageway through the connector; and the step of causingfluid to flow through the inner conduit comprises causing fluid to flowthrough the lumen of the support tube also.
 49. The method of claim 45further comprising urging the movable element to the first position sothat the bore is closed and the inner conduit has the first width duringthe step of retracting the blunt cannula from the first port of thehousing.